 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.progress;

 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.jobs.ISchedulingRule;
 import org.eclipse.ui.model.IWorkbenchAdapter;

 /**
  * This adapter interface provides support for lazy initialization of UI workbench elements
  * that are displayed visually. This adapter is used with an associated deferred content provider.
  *
  * @see DeferredTreeContentManager
  * @since 3.0
  */
 public interface IDeferredWorkbenchAdapter extends IWorkbenchAdapter {

     /**
      * Called by a job run in a separate thread to fetch the children of this adapter.
      * The adapter should in return notify of new children via the collector.
      * This is generally used when a content provider is getting elements.
      * <p>
      * It is good practice to check the passed in monitor for cancellation. This will
      * provide good responsiveness for cancellation requests made by the user.
      * </p>
      *
      * @param object the object to fetch the children for
      * @param collector the collector to notify about new children. Should not
      * be <code>null</code>.
      * @param monitor a progress monitor that will never be <code>null<code> to
      * support reporting and cancellation.
      */
     public void fetchDeferredChildren(Object object,
             IElementCollector collector, IProgressMonitor monitor);

     /**
      * Returns whether this adapter may have children. This is an optimized method
      * used by content providers to allow showing the [+] expand icon without having
      * yet fetched the children for the element.
      * <p>
      * If <code>false</code> is returned, then the content provider may assume
      * that this adapter has no children. If <code>true</code> is returned,
      * then the job manager may assume that this adapter may have children.
      * <p>
      *
      * @return <code>true</code>if the adapter may have childen, and <code>false</code>
      * otherwise.
      */
     public boolean isContainer();

     /**
      * Returns the rule used to schedule the deferred fetching of children for this adapter.
      *
      * @param object the object whose children are being fetched
      * @return the scheduling rule. May be <code>null</code>.
      * @see org.eclipse.core.runtime.jobs.Job#setRule(ISchedulingRule)
      */
     public ISchedulingRule getRule(Object object);
 }

